1) Field of the Invention
The present invention relates to a seal for a trocar and to a trocar with a seal.
2) Description of the Related Art
Trocars with seals, or seals for trocars, are known from the prior art and are used by specialists in a large number of operations on the eye.
In most cases, three trocars are normally used in an operation on the eye. Each trocar, also referred to as a guide tube, is introduced into the eye in such a way that the tip of the trocar extends into the vitreous body (corpus vitreum) of the eye, while the opposite end is available as an attachment. The eye in most cases has to be supplied with an infusion, which is done by way of what is called the infusion trocar. Two further trocars are also used in most cases. Suitable instruments or lighting devices can then be advanced to the eye through these further trocars. These further trocars are also referred to as instrument trocars or illuminating trocars.
A seal has to be provided between the trocars and the inserted instrument in order to avoid escape of a fluid when the trocar is in place. For example, the company DORC has started fitting a kind of cap on the flange of the trocar, which cap provides the seal between trocar and instrument. However, such a cap has the disadvantage of increasing the external diameter of the trocar.
U.S. Pat. No. 5,865,807 discloses a further seal that can be arranged in the inside of a trocar. This seal has two sealing locations. This is advantageous as regards the quality of the seal but has the disadvantage that the instruments have to be pushed in the longitudinal direction through two seals, causing greater forces to act on the eye.